1、Designation: D7205/D7205M 06 (Reapproved 2011)Standard Test Method forTensile Properties of Fiber Reinforced Polymer MatrixComposite Bars1This standard is issued under the fixed designation D7205/D7205M; the number immediately following the designation indicates theyear of original adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method determines the quasi-static longitudinaltensile strength and elongat
3、ion properties of fiber reinforcedpolymer matrix (FRP) composite bars commonly used astensile elements in reinforced, prestressed, or post-tensionedconcrete.NOTE 1Additional procedures for determining tensile properties ofpolymer matrix composites may be found in test methods D3039/D3039Mand D3916.1
4、.2 Linear elements used for reinforcing Portland cementconcrete are referred to as bars, rebar, rods, or tendons,depending on the specific application. This test method isapplicable to all such reinforcements within the limitationsnoted in the method. The test articles are referred to as bars inthis
5、 test method. In general, bars have solid cross-sections anda regular pattern of surface undulations and/or a coating ofbonded particles that promote mechanical interlock betweenthe bar and concrete. The test method is also appropriate foruse with linear segments cut from a grid. Specific details fo
6、rpreparing and testing of bars and grids are provided. In somecases, anchors may be necessary to prevent grip-induceddamage to the ends of the bar or grid. Recommended details forthe anchors are provided in Annex A1.1.3 The strength values provided by this method are short-term static strengths that
7、 do not account for sustained static orfatigue loading. Additional material characterization may berequired, especially for bars that are to be used under highlevels of sustained or repeated loading.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard
8、. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4.1 Within the text, the inch-pound units are shown inbrackets.1.5 This standard does
9、not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standa
10、rds:2A615/A615M Specification for Deformed and PlainCarbon-Steel Bars for Concrete ReinforcementD792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD883 Terminology Relating to PlasticsD3039/D3039M Test Method for Tensile Properties ofPolymer Matrix Comp
11、osite MaterialsD3171 Test Methods for Constituent Content of CompositeMaterialsD3878 Terminology for Composite MaterialsD3916 Test Method for Tensile Properties of PultrudedGlass-Fiber-Reinforced Plastic RodD5229/D5229M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Po
12、lymer Ma-trix Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical TestingE83 Practice for Verification and Classification of Exten-someter SystemsE122 Practice for Calculating Sample Size to Estimate,With Specified Precision, the
13、 Average for a Characteristicof a Lot or ProcessE456 Terminology Relating to Quality and StatisticsE1012 Practice for Verification of Test Frame and SpecimenAlignment Under Tensile and Compressive Axial ForceApplicationE1309 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Composite Materi
14、als in DatabasesE1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in Databases1This test method is under the jurisidiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.05 onStructural Test Methods.Current editio
15、n approved Aug. 1, 2011. Published December 2011. Originallyapproved in 2006. Last previous edition approved in 2006 as D7205/D7205M06.DOI: 10.1520/D7205_D7205M-06R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
16、Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.E1471 Guide for Identification of Fibers, Fillers, and CoreMaterials in Compute
17、rized Material Property Databases3. Terminology3.1 Terminology in D3878 defines terms relating to high-modulus fibers and their composites. Terminology in D883defines terms relating to plastics. Terminology in E6 definesterms relating to mechanical testing. Terminology in E456 andin Practice E122 de
18、fine terms relating to statistics and theselection of sample sizes. In the event of a conflict betweenterms, Terminology in D3878 shall have precedence over theother terminology standards.3.2 Definitions of Terms Specific to This Standard:3.2.1 anchor, na protective device placed on each end ofa bar
19、, between the bar and the grips of the tensile testingmachine, to prevent grip-induced damage. Usually used onbars with irregular surfaces, as opposed to flat strips wherebonded tabs are more typical.3.2.2 bar, na linear element, often with surface undula-tions or a coating of particles that promote
20、 mechanical inter-lock with concrete3.2.3 grid, na two-dimensional (planar) or three-dimensional (spatial) rigid array of interconnected FRP barsthat form a contiguous lattice that can be used to reinforceconcrete. The lattice can be manufactured with integrallyconnected bars or constructed of mecha
21、nically connectedindividual bars. The grid bar elements have transverse dimen-sions typically greater than 3 mm 0.125 in.3.2.4 effective diameter, na geometric value representingthe diameter of a circle which has an enclosed area equal to thenominal cross-sectional area of a bar.3.2.5 nominal cross-
22、sectional area, na measure of cross-sectional area of a bar, determined over at least one represen-tative length, used to calculate stress.3.2.6 nominal value, na value, existing in name only,assigned to a measurable property for the purpose of conve-nient designation. Tolerances may be applied to a
23、 nominalvalue to define an acceptable range for the property.3.2.7 representative length, nthe minimum length of a barthat contains a repeating geometric pattern that, placed end-to-end, reproduces the geometric pattern of a continuous bar(usually used in reference to bars having surface undulations
24、for enhancing interlock with concrete).3.2.8 standard cross-sectional area, nthe cross-sectionalarea of a standard numbered steel concrete reinforcing bar asgiven in ASTM A615/A615M, Table 1.3.2.9 surface undulation, nvariation in the area, orienta-tion, or shape of cross-section of a bar along its
25、length,intended to enhance mechanical interlock between a bar andconcrete, made by any of a number of processes such as, forexample, indentation, addition of extra materials, and twisting.3.3 Symbols:A = nominal cross-sectional area of a bar.CV = sample coefficient of variation, in percent.d = effec
26、tive bar diameterEchord= chord modulus of elasticity in the test direction.Ftu= ultimate tensile strength.L = free length of specimen (length between an-chors).La= anchor length.Lg= extensometer gage length.n = number of specimens.P = force carried by specimen.Pmax= maximum load carried by a test co
27、upon beforefailure.Sn1= sample standard deviation.xi= measured or derived property.x = sample mean (average).d = extensional displacement. = indicated normal strain from strain transducer.s = normal stress.4. Summary of Test Method4.1 A fiber reinforced polymer (FRP) bar, preferably fittedwith ancho
28、rs, is mounted in a mechanical testing machine andmonotonically loaded in tension to failure while recordingforce, longitudinal strain, and longitudinal displacement.4.2 Anchors as described in Annex A1 are recommendedbut not required. Alternative methods for attaching the speci-mens to the testing
29、machine are acceptable, but must allow forthe full strength of the bar to be developed and for the failureof the specimens to occur away from the attachments.5. Significance and Use5.1 This test method is designed to produce longitudinaltensile strength and elongation data. From a tension test, avar
30、iety of data are acquired that are needed for designpurposes. Material-related factors that influence the tensileresponse of bars and should therefore be reported include thefollowing: constituent materials, void content, volume percentreinforcement, methods of fabrication, and fiber reinforcementar
31、chitecture. Similarly, test factors relevant to the measuredtensile response of bars include specimen preparation, speci-men conditioning, environment of testing, specimen alignmentand gripping, and speed of testing. Properties, in the testdirection, that may be obtained from this test method includ
32、e:5.1.1 Ultimate tensile strength,5.1.2 Ultimate tensile strain,5.1.3 Tensile chord modulus of elasticity, and5.1.4 Stress-strain curve.6. Interferences6.1 The results from the procedures presented are limited tothe material and test factors listed in Section 5.6.2 GrippingThe method of gripping has
33、 been known tocause premature tensile failures in bars. Anchors, if used,should be designed in such a way that the full tensile capacitycan be achieved without slip throughout the length of theanchor during the test.6.3 System AlignmentExcessive bending may cause pre-mature failure, as well as a hig
34、hly inaccurate modulus ofelasticity determination. Every effort should be made to elimi-nate bending from the test system. Bending may occur due tomisalignment of the bar within anchors or grips or associatedfixturing, or from the specimen itself if improperly installed inthe grips or if it is out-o
35、f-tolerance due to poor specimenD7205/D7205M 06 (2011)2preparation. See ASTM E1012 for verification of specimenalignment under tensile loading.6.4 Measurement of Cross-Sectional AreaThe nominalcross-sectional area of the bar is measured by immersing aprescribed length of the specimen in water to det
36、ermine itsbuoyant weight. Bar configurations that trap air during immer-sion (aside from minor porosity) cannot be assessed using thismethod. This method may not be appropriate for bars that havelarge variations in cross-sectional area along the length of thebar.7. Apparatus7.1 MicrometersThe microm
37、eter(s) shall use a suitablesize diameter ball-interface on irregular surfaces and a flatanvil interface on machined edges or very-smooth tooledsurfaces. The accuracy of the instruments shall be suitable forreading to within 1 % of the intended measurement.7.2 Testing MachineThe testing machine shal
38、l be inconformance with Practice E4, and shall satisfy the followingrequirements:7.2.1 Testing Machine HeadsThe testing machine shallhave both an essentially stationary head and a movable head.7.2.2 Drive MechanismThe testing machine drive mecha-nism shall be capable of imparting to the movable head
39、 acontrolled displacement rate with respect to the stationaryhead. The displacement rate of the movable head shall becapable of being regulated as specified in 11.3.7.2.3 Force IndicatorThe testing machine force-sensingdevice shall be capable of indicating the total force beingcarried by the specime
40、n. This device shall be essentially freefrom inertia-lag at the specified rate of testing and shallindicate the force with an accuracy over the load range(s) ofinterest of within 6 1 % of the indicated value, as specified byPractices E4. The force range(s) of interest may be fairly lowfor modulus ev
41、aluation, much higher for strength evaluation, orboth, as required.NOTE 2Obtaining precision force data over a large range of interest inthe same test, such as when both elastic modulus and ultimate force arebeing determined, place extreme requirements on the force transducer andits calibration. For
42、 some equipment a special calibration may be required.For some combinations of material and force transducer, simultaneousprecision measurement of both elastic modulus and ultimate strength maynot be possible, and measurement of modulus and strength may have to beperformed in separate tests using a
43、different force transducer range foreach test.7.2.4 GripsIf grips are used, each head of the testingmachine shall carry one grip for holding the specimen so thatthe loading direction is coincident with the longitudinal axis ofthe specimen. The grips shall apply sufficient lateral pressure toprevent
44、slippage between the grip face and the specimen oranchor. It is highly desirable to use grips that are rotationallyself-aligning to minimize bending stresses in the specimen.The grips shall be aligned in accordance with ASTM E1012and shall not bias failure location in the bar.7.3 AnchorsUse of a rig
45、id pipe-shaped anchor as aninterface between the bar and the grips or loading head of thetesting machine is recommended to prevent stress concentra-tions and consequent downward biasing of measured strength.Details of recommended anchors are provided in Annex A1.7.3.1 Attachment of anchors to loadin
46、g heads shall be bythreaded connectors between the anchors and loading head orby grips. Details of this attachment are shown in Fig. A1.3.7.4 Strain-Indicating DeviceLongitudinal strain shall bemeasured by an appropriate strain transducer as long asattachment of this device does not cause damage to
47、the bar (seeNote 3).NOTE 3For most bars the application of surface-bonded strain gagesis impractical due to surface undulations (for example, braided, twisted,and indented bars). Strain gages of a suitable gage length can be used ifthe surface of the bar can be smoothed with a polymer resin such as
48、epoxyto provide a suitable bonding surface so that measurements are equivalentto those provided by an extensometer meeting the requirements of section7.4.1.7.4.1 ExtensometersExtensometers shall satisfy, at aminimum, Practice E83, Class B-2 requirements for the strainrange of interest, and shall be
49、calibrated over that strain rangein accordance with Practice E83. The extensometer shall beessentially free of inertia-lag at the specified speed of testing.The gage length of the extensometer, Lg, shall be not less thaneight times the effective bar diameter, nor less than onerepresentative length. The extensometer shall be centered onthe mid-length position of the bar, not less than eight effectivebar diameters from either anchor7.4.1.1 Temperature compensation is recommended whennot testing at Standard Laboratory Atmosphere. When appro-priate, use eith
